Viscous settable fluid for lost circulation in subterranean formations

Abstract

A method of treating a well the method including the steps of: (A) forming a fluid including: (i) a shear-thinning aqueous liquid phase; and (ii) an inorganic setting material; wherein the fluid is shear-thinning, pumpable, and settable; and (B) introducing the fluid into the well.

What is claimed is: 
     
       1. A composition comprising:
 (i) an aqueous liquid phase that comprises a nano-particulate sol; 
 (ii) an inorganic setting material dissolved in the aqueous liquid phase; and 
 (iii) a water-soluble chemical activator selected from the group consisting of: (a) phytic acid; an alkali metal salt or ammonium salt thereof; (b) methylglycinediacetic acid, an alkali metal salt or ammonium salt thereof; and (c) salicylic acid, ascorbic acid, tannic acid, and an alkali metal salt or ammonium salt of any of the foregoing, 
 wherein the composition has a pH between 5 and 7 and is pumpable and settable. 
 
     
     
       2. The composition according to  claim 1 , wherein the composition forms a solid within at most 0.5 hours at a temperature as least as high as a design temperature for the composition. 
     
     
       3. The composition according to  claim 1 , wherein the aqueous liquid phase comprises water, a viscosity-increasing agent, and a cross-linking agent. 
     
     
       4. The composition according to  claim 3 , wherein the viscosity-increasing agent is a water-soluble polysaccharide. 
     
     
       5. The composition according to  claim 4 , wherein the viscosity-increasing agent comprises a guar derivative. 
     
     
       6. The composition according to  claim 4 , wherein the cross-linking agent is a borate compound. 
     
     
       7. The composition according to  claim 3 , wherein the aqueous liquid phase comprises a water-soluble inorganic salt. 
     
     
       8. The composition according to  claim 1 , wherein the nano-particulate sol comprises a silica sol. 
     
     
       9. The composition according to  claim 8 , wherein the aqueous liquid phase comprises a water-soluble inorganic salt. 
     
     
       10. The composition according to  claim 8 , wherein the aqueous liquid phase has an ionic strength less than 0.75. 
     
     
       11. The composition according to  claim 1 , wherein the inorganic setting material is a water-soluble silicate. 
     
     
       12. The composition according to  claim 1  further comprising a lost-circulation material. 
     
     
       13. The composition according to  claim 12 , wherein the lost-circulation material is selected from the group consisting of: marble, calcium carbonate, calcium magnesium carbonate, walnut shells, graphites, fibers, cellulosic materials, and any combination thereof. 
     
     
       14. The composition according to  claim 12 , wherein the lost-circulation material has a particulate size of at least 5 microns. 
     
     
       15. The composition according to  claim 1 , wherein the composition does not include fibers. 
     
     
       16. A composition comprising:
 (i) an aqueous liquid phase that comprises a nano-particulate sol; 
 (ii) an inorganic setting material dissolved in the aqueous liquid phase; and 
 (iii) a water-soluble chemical activator selected from the group consisting of: (a) phytic acid; an alkali metal salt or ammonium salt thereof; (b) methylglycinediacetic acid, an alkali metal salt or ammonium salt thereof; and (c) salicylic acid, ascorbic acid, tannic acid, and an alkali metal salt or ammonium salt of any of the foregoing, 
 wherein the composition is pumpable and settable. 
 
     
     
       17. The composition according to  claim 16 , wherein the viscosity-increasing agent is a water-soluble polysaccharide. 
     
     
       18. The composition according to  claim 16 , wherein the nano-particulate sol comprises a silica sol. 
     
     
       19. The composition according to  claim 16 , wherein the inorganic setting material is a water-soluble silicate. 
     
     
       20. The composition according to  claim 16 , wherein the composition does not include fibers.